Soldier-turned-artist Chen Guang was released yesterday, more than a month after he was detained in Beijing ahead of the 25th anniversary of the military crackdown on pro-democracy protests, his friend said.

Chen was among those detained by the government bent on preventing any commemoration of the suppression that took place in and around Tiananmen Square on June 3-4, 1989.

Beijing does not allow public discussions of the event and even discourages private conversations about it. The government also has tried to deter foreign media from covering the anniversary with threats of unspecified consequences.

Moves to control activists were particularly harsh this year, as more people than in previous years were detained, put under house arrest or forced to leave their cities of residence weeks before the anniversary.

Most have been released since June 4, although the prominent rights lawyer Pu Zhiqiang was formally arrested on Friday on suspicion of "creating a disturbance" and "illegally obtaining personal information". Pu was seized as he attended a private commemoration.

Chen witnessed the crackdown as a soldier in 1989. His detention is believed to be connected to a private art performance, where he whitewashed over walls of painted year numbers from 1989 on.

"[This performance is about] what has happened to us, to me, to society," he said in an interview a week before public security officers detained him and seized several of his paintings. "It is meant to be a reflection of why we have not made a correct and fair assessment of what happened 25 years ago."

Friend Melanie Wang said he had been freed, although he could not be immediately reached yesterday, and calls to the Tongzhou Detention Centre were unanswered. But his friends shared on social media a photo of Chen, smiling and wearing a V-necked T-shirt as he walked out of the detention centre.

Another artist, Guo Jian, was also seized before the anniversary and after a profile of him appeared in the Financial Times newspaper. Guo is expected to be repatriated to Australia, where he is a citizen.

This article appeared in the South China Morning Post print edition as Artist Chen Guang freed after June 4 arrest